package homework;

import java.util.Stack;

//力扣232题、用栈实现队列（简单）
public class MyQueue {
    Stack<Integer> stack1;
    Stack<Integer> stack2;

    public MyQueue() {
        stack1 = new Stack<>();
        stack2 = new Stack<>();
    }

    public void push(int x) {
        stack1.push(x);
    }

    public int pop() {
        if (empty()){
            return -1;
        }
        if (stack2.empty()){
            while (!stack1.empty()){
                stack2.push(stack1.pop());
            }
        }//不要忘了判断stack2是否为空
        return stack2.pop();
    }

    public int peek() {
        if (empty()){
            return -1;
        }
        if (stack2.empty()){
            while (!stack1.empty()){
                stack2.push(stack1.pop());
            }
        }

        return stack2.peek();
    }

    public boolean empty() {
        return stack1.empty() && stack2.empty();
    }
}
